Density map as a function of the first and second principal component of the galaxies of the validation sample. In the bottom panel, we included the galaxies of the training sample (red dots) and the limit in the principal components of the galaxies for which DNF provides a value of photo-z with an uncertainty, DNF_ZSIGMA < 1.0 (orange line) and DNF_ZSIGMA < 0.1 (bold black line), with this training sample.